1. Line two baking sheets with parchment paper or silicone mats and prepare a piping bag with a round tip.

2. Sift the almond flour and powdered sugar together into a bowl to remove lumps and create a smooth dry mixture.

3. In a clean mixing bowl, beat the egg whites until foamy, then add the cream of tartar and slowly stream in the granulated sugar.

4. Continue beating until stiff glossy peaks form, then mix in the vanilla extract and white gel food coloring if using.

5. Fold the dry ingredients into the meringue in batches until the batter flows in a thick ribbon and slowly settles back into itself.

6. Pipe small circles onto the prepared baking sheets, tap the pans on the counter, and pop any visible air bubbles with a toothpick.

7. Let the shells rest for 30 to 45 minutes, or until the tops feel dry to the touch.

8. Bake one tray at a time at 300°F for 14 to 17 minutes, then cool the shells completely before removing them.

9. Beat the butter until creamy, then mix in the powdered sugar, heavy cream, and melted white chocolate until smooth.

10. Match the shells by size, pipe the filling onto half of them, sandwich with the remaining shells, and decorate with snowflake sprinkles or edible shimmer.

11. Refrigerate the filled macarons for 24 hours before serving for the best texture.